The invention relates to a method for controlling the distance between moving motor vehicles. When automatically maintaining the distance between motor vehicles, a set distance is usually observed depending upon the speed. However, from experience it is known that this distance is actually only accepted by a small number of motorists. Therefore, unsteady states frequently occur which ultimately frustrate the implementation or maintenance of an optimum following distance of vehicles.
U.S. Pat. No. 5,014,200 discloses a system for the control of the travel speed of a vehicle, which system serves to observe a predetermined distance between the vehicle and a vehicle in front. In order to measure the distance and the relative speed between the two vehicles, a radar device is used in the following vehicle. Here, a critical distance between the vehicles is determined using the reaction time of the driver of the vehicle and is updated as a function of the vehicle's own speed. For this purpose, the driver of the vehicle enters his personal reaction time into the system. However, this intervention facility of the driver of the vehicle puts the effectiveness of such a system in doubt.
There is therefore needed a method for controlling the distance between moving motor vehicles, which method leads in practice to the distance between vehicles being automatically maintained in a way which finds a better degree of acceptance with drivers.
This need is met by a method of the generic type for controlling the distance between moving motor vehicles. The vehicle behind is equipped with an overridable automatic speed control and distance detection means and a current set distance which is to be specified to the distance controller being updated as a function of the vehicle's own detected current speed V.sub.e as S.sub.s =(V.sub.e * Tr).
The method includes the steps of:
(1) stipulating a bandwidth for the admissible reaction time T.sub.r between a lower limit value T.sub.rmin and an upper limit value T.sub.rmax ; PA1 (2) the following events are detected: PA1 (4) The reaction time T.sub.r remains unchanged if an event (a), (b) or (c) occurs within a predetermined adaptation time T.sub.ad, and is changed if an event (a), (b) or (c) occurs after the said adaptation time T.sub.ad expires in the event of (a) or (b), the current reaction time T.sub.r is reduced according to the following rule: EQU T.sub.r =T.sub.r -T.sub.d, if T.sub.r is greater than T.sub.rmin ; EQU T.sub.r =T.sub.rmin, if T.sub.r is equal to T.sub.rmin,
(a) overtaking maneuvers by monitoring at least one of steering and indicator lights; PA2 (b) overrides of the automatic speed control by accelerating by monitoring the accelerator pedal; PA2 (c) overrides of the automatic speed control by braking by monitoring the brake pedal; PA2 (3) determining the initial set distance S.sub.0 which is to be specified to the distance controller on the basis of a permanently stored average reaction time T.sub.rmit and then used for initial control with T.sub.r =T.sub.rmit ;
where T.sub.d is the adaptation decrement, and in the event of (c) the current reaction time T.sub.r is increased according to the following rule: EQU T.sub.r =T.sub.r +T.sub.d, if T.sub.r is smaller than T.sub.rmax ; EQU T.sub.r =T.sub.rmax, if T.sub.r is equal to T.sub.rmax
where T.sub.d is the adaptation increment.
According to the present invention, the driver interventions which occur in the course of a currently maintained distance control are detected and evaluated. For this, control means which are actuated in the course of the normal travel mode, for example the accelerator pedal, the brake pedal, the indicator lights, etc. are monitored- Conclusions are made as to the driver's current wish or driving preferences from an evaluation of the driver's detected actuations and the driver's reaction time, included in the currently calculated set distance, is accordingly adaptively corrected.
In this manner, dead times are minimized and the most rapid possible adaptation of the distance between vehicles to changing driving behavior of the driver is achieved. As a result, a significantly improved acceptance for a corresponding automatic distance control can be detected.